This invention relates to an improved sequential hydrocracking and hydrogenating process for the production of UV-stable lube oils. More particularly, it relates to the use of an improved catalyst for the hydrogenating step of the sequential process.
Lube oils produced by hydrocracking heavy oils such as vacuum gas oils and deasphalted residuum oils are well known for their poor stabilities as shown by the UV stability test described below. Representative methods for alleviating this problem are described in U.S. Pat. Nos. 3,666,657 (S. L. Thompson et al) and 3,852,207 (B. E. Stangeland et al). Nevertheless, there remains a need for process improvements, for example in terms of milder conditions and/or less costly catalysts.
An object herein is to provide an improved sequential hydrocracking and hydrotreating process for the production of lubricating oil from the aforementioned hydrocarbon feedstocks.